Earlier in the day, the parliamentary legislation and judiciary committee approved the bill despite objections from some ruling party members, who took issue with a clause that lets only opposition parties pick the independent counsel.

Under the bill, two candidates for independent counsel will be recommended by the main opposition Democratic Party and the splinter People's Party, with the president being allowed to designate one of them.

The special probe team, which will consist of more than 60 staffers including 20 prosecutors, has up to four months to complete the investigation.

Choi, who has been friends with Park for more than 40 years, was arrested earlier this month for abuse of power and attempted fraud. She allegedly exercised influence over key state affairs, though she has no government position. She is also suspected of using her ties with Park for financial gain and personal favors.'